Others have written about violence. A member of the Facebook group wrote on Wednesday: "It will take more than one conversation to fix the problem." Below this post, another member replied with emojis from explosions.
On Thursday morning, Facebook group Stop the Steal continued to grow, according to data from CrowdTangle, a Facebook-owned social media analytics tool.
At this point, right-wing figures like Jack Posobiec, a pro-Trump activist, and Amy Kremer, Ms. Kremer's mother and founder of a group called Women for Trump, started posting on Twitter through the Facebook group. Ali Alexander, a political activist previously known as Ali Akbar, tweeted dozens of times to his 140,000 Twitter followers about the Stop the Steal movement.
Her messages, shared thousands of times, were a rallying call for people to join the Stop the Steal Facebook group and take part in local anti-election fraud protests.
"In just the first few hours, more than 100,000 people joined the Women for America First, Stop the Steal Facebook group," wrote Posobiec. In the comments below his post, many people hailed the Facebook group's popularity.
The tweets helped send more people to Stop the Steal. Interactions with the Facebook group rose to 36 posts per minute on Thursday morning, up from roughly one post per minute according to CrowdTangle data.
Mr. Posobiec, Mr. Alexander and Amy Kremer did not immediately respond to requests for comment.
On Facebook, executives were briefed on the group by Facebook moderators when they began flagging posts for potential calls for violence and protests to disrupt voting. The company also received calls from journalists about the group and its explosive growth. By mid-morning executives were discussing whether to remove Stop the Steal, said an employee involved in the discussions who was not authorized to speak publicly.